No. "В деревья" does not make any sense in Russian (unless those kids are actually some kind of larvae who can can get inside the tree trunks). Деревья cannot be used in Russian in the sense of "arbour" or "woods". You can say "в рощу" (into an/the arbour), "в лес" (into the woods) etc., but not в деревья".
But what if a I am a squirrel and if there is a hole in the three where I store my acorns. Could I say «Я иду в деревья»?
Firstly, you would not use the verb "ходить" for a squirrel-like animal. Ходить means "to walk" when applied to animals or birds, all other possible meanings would not be applicable to them. Elephants, horses, dogs walk (when they are not running), squires either run or climb. The corresponding verbs would be "бегать" and "лазать".
But even if you fix the verb, the sentence would still sound extremely awkward in Russian. I have never seen "в деревья (plural)" used to indicate the direction of motion.
My bad, I should have used "идти" rather than "ходить", but that does not change anything: you use the two verbs in exactly the same way; the only difference is that "ходить" is multi-directional and is used for back-an-forth or repetitive action, while "идти" is unidirectional. In others words, if you can use one, you can use the other and vice versa.
So, no, a squirrel cannot "идти", full stop.
And one cannot "идти" to either "в" or "на деревья".
Yes, that may be true. The thing is, I did not the verb ходить in my sentence and it isn’t even used in the sentence above (‘The children are walking towards the trees.’), I used it’s concrete/uni-directional correspondent, the verb идти: «Я иду в деревья.»
Ok, you have never heard «в деревья» in indicate direction, have you heard «на деревья» for that meaning? Would «Я иду на деревья» be possible?
Then how do you say "the squirrel goes into the tree" (where its home is) in Russian?
Well, I got a different opinion from another native speaker, but maybe she was thinking of the literally "into the trees" meaning. Certainly I've always seen "в лес".
More precisely = dative plural.
I wish DL diagramed each answer in "cases" when completed answers were shown.
I've taken to color-coded pens and writing everything down myself to drive it home.
So I thought O (in nominative single case) was replaced with aM in dative plural case but we can't use this rule here because the nominative plural form is irregular. Who concocted all this complexity?